Moved explanation of the room model to a separate user's guide.

This change has been made to facilitate the documentation of the FFD model.
Moved explanation of the room model to a separate user's guide.

This change has been made to facilitate the documentation of the FFD model.
Changed connectors for ticket #165.
Changed connector for issue #165.
Updated reference results for issue #165.

Minor differences due to change in numerics.
Removed sum where it is not needed. (Issue #165)
Updated documentation for issue #165.
Updated the documentation by changing species with moisture
Merge pull request #166 from lbl-srg/massBalance

Revise mass balance
Merge branch 'master' into districtsLoad